Quiz

Test your understanding of the concepts covered in the Webapps with Docker chapter.

Q1. In `docker run -p 8888:5000 myapp`, what does the port mapping `-p 8888:5000` specify?

A It maps host port 8888 to container port 5000 B It maps container port 8888 to host port 5000 C It restricts memory usage to 8888 MB and CPU to 5000 MHz D It assigns random IP addresses between 8888 and 5000

Explanation

Syntax `-p [HOST_PORT]:[CONTAINER_PORT]` maps traffic arriving at port 8888 on your host machine to port 5000 inside the container.

Q2. Which Dockerfile instruction sets the base image for subsequent build instructions?

A FROM B BASE C INIT D IMAGE

Explanation

The `FROM` instruction initializes a new build stage and specifies the base image (e.g. `python:3.12-slim`) upon which your image is constructed.

Q3. Why is it a best practice to copy `requirements.txt` and run `pip install` BEFORE copying the rest of your application code (`COPY . .`)?

A Because Python will fail if requirements.txt is copied at the same time as application code B To leverage Docker's layer caching so unchanged dependency installation layers are reused during code edits C Because `COPY . .` deletes any previously existing files in the container D To reduce container disk footprint on AWS

Explanation

Docker caches each build step layer. By installing dependencies first, Docker reuses the cached `pip install` layer when only application source code changes.

Q4. What is the primary difference between `RUN` and `CMD` in a Dockerfile?

A `RUN` executes commands during image build to produce new layers, while `CMD` specifies default execution when launching a container B `RUN` executes when starting a container, while `CMD` executes at build time C `RUN` is for setting environment variables, while `CMD` is for copying files D There is no difference; `RUN` and `CMD` are identical aliases

Explanation

`RUN` executes shell commands during `docker build` to construct image layers. `CMD` specifies the default command executed when running `docker run`.

Q5. When deploying a single-container application to AWS Elastic Beanstalk, what file is uploaded to configure image name and port mapping?

A Dockerrun.aws.json B aws-compose.yml C Dockerfile.aws D beanstalk.config

Explanation

`Dockerrun.aws.json` is the AWS-specific configuration file that tells Elastic Beanstalk which Docker image to pull and which ports to expose.

Score: 0 / 5

Reset Quiz